Whole House Heat Loss Calculator

Total Heat Loss Formula:

\[ \text{Total Heat Loss} = \sum (U \times A \times \Delta T) + \text{Infiltration} \]

U-value (U):

BTU/(hr·ft²·°F)

Area (A):

ft²

Temperature Difference (ΔT):

°F

Infiltration Heat Loss:

BTU/hr

Total Heat Loss:

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1. What is Whole House Heat Loss?

Whole house heat loss refers to the total amount of heat energy that escapes from a building through various surfaces and air infiltration. Understanding this value is crucial for proper HVAC system sizing and energy efficiency improvements.

2. How Does the Calculator Work?

The calculator uses the fundamental heat loss formula:

\[ \text{Total Heat Loss} = \sum (U \times A \times \Delta T) + \text{Infiltration} \]

Where:

\( U \) — U-value (thermal transmittance) in BTU/(hr·ft²·°F)
\( A \) — Surface area in square feet (ft²)
\( \Delta T \) — Temperature difference between inside and outside in °F
\( \text{Infiltration} \) — Heat loss due to air leakage in BTU/hr

Explanation: This calculation accounts for conductive heat loss through building surfaces and convective heat loss through air infiltration.

3. Importance of Heat Loss Calculation

Details: Accurate heat loss calculation is essential for proper HVAC system sizing, energy efficiency analysis, insulation planning, and ensuring occupant comfort while minimizing energy costs.

4. Using the Calculator

Tips: Enter U-value in BTU/(hr·ft²·°F), area in square feet, temperature difference in °F, and infiltration heat loss in BTU/hr. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is U-value and how do I find it?
A: U-value measures how well a building element conducts heat. Lower values indicate better insulation. Check manufacturer specifications or use standard values for common materials.

Q2: How do I calculate temperature difference?
A: ΔT = (Indoor temperature) - (Outdoor design temperature). Use local climate data for appropriate outdoor design temperatures.

Q3: What is infiltration heat loss?
A: Heat lost through air leaks in the building envelope. This can be estimated using blower door tests or standard values based on building tightness.

Q4: Should I calculate for each surface separately?
A: For accurate whole-house calculation, sum the heat loss through walls, windows, doors, roof, and floor separately, then add infiltration losses.

Q5: How does this help with HVAC sizing?
A: Total heat loss determines the heating capacity needed. Oversized systems cycle frequently, reducing efficiency and comfort.